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idr: reorder the fields 

idr_layer->layer is always accessed in read path, move it in the front.

idr_layer->bitmap is moved on the bottom.  And rcu_head shares with
bitmap due to they do not be accessed at the same time.

idr->id_free/id_free_cnt/lock are free list fields, and moved to the
bottom.  They will be removed in near future.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Lai Jiangshan 2014-06-06 14:37:15 -07:00 committed by Linus Torvalds
parent 15f3ec3f23
commit dcbff5d1ef
1 changed files with 8 additions and 5 deletions
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13
include/linux/idr.h
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@ -29,21 +29,24 @@
struct idr_layer { struct idr_layer {
int prefix; /* the ID prefix of this idr_layer */ int prefix; /* the ID prefix of this idr_layer */
DECLARE_BITMAP(bitmap, IDR_SIZE); /* A zero bit means "space here" */ int layer; /* distance from leaf */
struct idr_layer __rcu *ary[1<<IDR_BITS]; struct idr_layer __rcu *ary[1<<IDR_BITS];
int count; /* When zero, we can release it */ int count; /* When zero, we can release it */
int layer; /* distance from leaf */ union {
struct rcu_head rcu_head; /* A zero bit means "space here" */
DECLARE_BITMAP(bitmap, IDR_SIZE);
struct rcu_head rcu_head;
};
}; };
struct idr { struct idr {
struct idr_layer __rcu *hint; /* the last layer allocated from */ struct idr_layer __rcu *hint; /* the last layer allocated from */
struct idr_layer __rcu *top; struct idr_layer __rcu *top;
struct idr_layer *id_free;
int layers; /* only valid w/o concurrent changes */ int layers; /* only valid w/o concurrent changes */
int id_free_cnt;
int cur; /* current pos for cyclic allocation */ int cur; /* current pos for cyclic allocation */
spinlock_t lock; spinlock_t lock;
int id_free_cnt;
struct idr_layer *id_free;
}; };
#define IDR_INIT(name) \ #define IDR_INIT(name) \